For problem statement at 0-999/200-299/220-229/225/problemD.txt this is a correct solution, but verifier at 0-999/200-299/220-229/225/verifierD.go ends with All tests passed can you fix the verifier? ```go
package main

import (
	"fmt"
)

var dr = []int{-1, 0, 1, 0}
var dc = []int{0, 1, 0, -1}

func getDir(r1, c1, r2, c2 int) int {
	if r2-r1 == -1 && c2 == c1 {
		return 0
	}
	if r2 == r1 && c2-c1 == 1 {
		return 1
	}
	if r2-r1 == 1 && c2 == c1 {
		return 2
	}
	if r2 == r1 && c2-c1 == -1 {
		return 3
	}
	return -1
}

func collides(nr, nc, r, c, dirs, k int) bool {
	if nr == r && nc == c {
		return true
	}
	for i := 0; i < k-2; i++ {
		dir := (dirs >> (2 * i)) & 3
		r += dr[dir]
		c += dc[dir]
		if nr == r && nc == c {
			return true
		}
	}
	return false
}

func main() {
	var n, m int
	if _, err := fmt.Scan(&n, &m); err != nil {
		return
	}

	grid := make([]string, n)
	for i := 0; i < n; i++ {
		fmt.Scan(&grid[i])
	}

	pos := make([]struct{ r, c int }, 10)
	k := 0
	target_r, target_c := -1, -1

	for r := 0; r < n; r++ {
		for c := 0; c < m; c++ {
			ch := grid[r][c]
			if ch >= '1' && ch <= '9' {
				idx := int(ch - '0')
				pos[idx] = struct{ r, c int }{r, c}
				if idx > k {
					k = idx
				}
			} else if ch == '@' {
				target_r = r
				target_c = c
			}
		}
	}

	start_r, start_c := pos[1].r, pos[1].c
	dirs := 0
	for i := 1; i < k; i++ {
		d := getDir(pos[i].r, pos[i].c, pos[i+1].r, pos[i+1].c)
		dirs |= d << (2 * (i - 1))
	}
	start_state := uint32(start_r<<20 | start_c<<16 | dirs)

	dist := make([]uint16, 1<<24)
	queue := make([]uint32, 0, 1000000)

	queue = append(queue, start_state)
	dist[start_state] = 1

	mask := (1 << (2 * (k - 1))) - 1
	head_idx := 0

	for head_idx < len(queue) {
		state := queue[head_idx]
		head_idx++

		r := int((state >> 20) & 15)
		c := int((state >> 16) & 15)
		dirs := int(state & 0xFFFF)

		if r == target_r && c == target_c {
			fmt.Println(dist[state] - 1)
			return
		}

		d_val := dist[state]

		for d := 0; d < 4; d++ {
			nr := r + dr[d]
			nc := c + dc[d]

			if nr < 0 || nr >= n || nc < 0 || nc >= m {
				continue
			}
			if grid[nr][nc] == '#' {
				continue
			}

			if collides(nr, nc, r, c, dirs, k) {
				continue
			}

			ndirs := ((dirs << 2) & mask) | (d ^ 2)
			nstate := uint32(nr<<20 | nc<<16 | ndirs)

			if dist[nstate] == 0 {
				dist[nstate] = d_val + 1
				queue = append(queue, nstate)
			}
		}
	}
	fmt.Println(-1)
}
```